1. Field of the Invention
The present invention relates to devices and methods for delivering a prosthesis to a desired location in the body and methods for achieving delivery and implantation of a prosthesis. More particularly, the present invention relates to a delivery system for deploying prostheses within a body lumen and to methods of delivering prostheses to a desired location in a body. The delivery system includes a handle that can be operated with one hand while maintaining accuracy in deployment of a prosthesis in a body lumen.
2. Background
Vascular aneurysms are the result of abnormal dilation of a blood vessel, usually resulting from disease and/or genetic predisposition, which weakened the arterial wall and allowed it to expand. While aneurysms could occur in any blood vessel, most occur in the aorta and peripheral arteries, with the majority of aortic aneurysms occurring in the abdominal aorta, usually beginning below the renal arteries and often extending into one or both of the iliac arteries.
Aortic aneurysms were commonly treated in open surgical procedures where the diseased vessel segment was bypassed and repaired with an artificial vascular graft. While considered to be an effective surgical technique, particularly considering the alternative of a fatal ruptured abdominal aortic aneurysm, conventional vascular graft surgery suffered from a number of disadvantages. The surgical procedure was complex and required experienced surgeons and well-equipped surgical facilities. Even with the best surgeons and equipment, however, patients being treated frequently were elderly and weakened from cardiovascular and other diseases, reducing the number of eligible patients.
Even for eligible patients prior to rupture, conventional aneurysm repair had a relatively high mortality rate, usually from 2% to 10%. Morbidity related to the conventional surgery included myocardial infarction, renal failure, impotence, paralysis, and other conditions. Additionally, even with successful surgery, recovery took several weeks, and often required a lengthy hospital stay.
In order to overcome some or all of these drawbacks, endovascular prosthesis placement for the treatment of aneurysms has been used. Although very promising, many of the proposed methods and apparatus suffered from undesirable limitations. In particular, accurate delivery and placement of the endovascular prosthesis within the vasculature was problematic.
Stent-grafts (endovascular prostheses) were resilient structures, usually biased to expand against the surrounding lumenal wall. Such resiliently-expanding stent-grafts were tightly compressed within the catheter, imposing significant radial expansion forces against the surrounding catheter sheath. This often led to excess friction between the stent-graft and the sheath, particularly when the resiliently-expanding structure becomes partially embedded in the catheter material. Thus, the delivery system had to be capable of imparting a significant, yet controlled, force to retract the sheath and deploy the stent-grafts.
U.S. Pat. No. 7,419,501 to Chiu et al., which is incorporated herein by reference in its entirety, discloses a delivery system that attempts to address these issues by providing a delivery system having a handle that allows for more accurate placement of a stent-graft in a body lumen. The delivery system includes a sheath and a handle. The handle includes a slide shaft having a threaded outer surface, and a hub assembly coupled to the sheath. The hub assembly includes an inner slider having a thread tooth pivot support, a thread tooth pivotably mounted to the thread tooth pivot support, and a sleeve having a thread tooth press member pressing on the thread tooth, where motion of the sleeve relative to the inner slider pivots the thread tooth on the thread tooth pivot support to engage and disengage the hub assembly with the threaded outer surface. FIGS. 1-2 and 4-7 of the present application have been adapted from figures originally presented in U.S. Pat. No. 7,419,501.